This invention relates to an ink jet recording element. More particularly, this invention relates to an ink jet recording element containing encapsulated particles.
In a typical ink jet recording or printing system, ink droplets are ejected from a nozzle at high speed towards a recording element or medium to produce an image on the medium. The ink droplets, or recording liquid, generally comprise a recording agent, such as a dye or pigment, and a large amount of solvent. The solvent, or carrier liquid, typically is made up of water, an organic material such as a monohydric alcohol, a polyhydric alcohol or mixtures thereof.
An ink jet recording element typically comprises a support having on at least one surface thereof an ink-receiving or image-forming layer, and includes those intended for reflection viewing, which have an opaque support, and those intended for viewing by transmitted light, which have a transparent support.
While a wide variety of different types of image-recording elements for use with ink jet devices have been proposed heretofore, there are many unsolved problems in the art and many deficiencies in the known products which have limited their commercial usefulness.
It is well known that in order to achieve and maintain photographic-quality images on such an image-recording element, an ink jet recording element must:
Be readily wetted so there is no puddling, i.e., coalescence of adjacent ink dots, which leads to non-uniform density
Exhibit no image bleeding
Exhibit the ability to absorb high concentrations of ink and dry quickly to avoid elements blocking together when stacked against subsequent prints or other surfaces
Exhibit no discontinuities or defects due to interactions between the support and/or layer(s), such as cracking, repellencies, comb lines and the like
Not allow unabsorbed dyes to aggregate at the free surface causing dye crystallization, which results in bloom or bronzing effects in the imaged areas
Have an optimized image fastness to avoid fade from contact with water or radiation by daylight, tungsten light, or fluorescent light
An ink jet recording element that simultaneously provides an almost instantaneous ink dry time and good image quality is desirable. However, given the wide range of ink compositions and ink volumes that a recording element needs to accommodate, these requirements of ink jet recording media are difficult to achieve simultaneously.
Ink jet recording elements are known that employ porous or non-porous single layer or multilayer coatings that act as suitable image receiving layers on one or both sides of a porous or non-porous support. Recording elements that use non-porous coatings typically have good image quality but exhibit poor ink dry time. Recording elements that use porous coatings typically contain colloidal particulates and have poorer image quality but exhibit superior dry times.
While a wide variety of different types of porous image-recording elements for use with ink jet printing are known, there are many unsolved problems in the art and many deficiencies in the known products which have severely limited their commercial usefulness. The challenge of making a porous image-recording layer is to achieve a high gloss level without cracking, high color density, and a fast drying time.
EP 813,978 relates to an ink jet recording element wherein an ink absorption layer is used comprising fine particles, a hydrophilic binder and oil drops. However, there is a problem with this element in that the oil drops will migrate to the surface and cause changes in the appearance of the image.
It is an object of this invention to provide an ink jet recording element that has a fast ink dry time. It is another object of this invention to provide an ink jet recording element that has good image quality.
These and other objects are achieved in accordance with the invention which comprises an ink jet recording element comprising a substrate having thereon an image-receiving layer comprising inorganic particles encapsulated with an organic polymer having a Tg of less than about 20xc2x0 C., the weight ratio of the inorganic particles to the organic polymer being from about 20 to about 0.2.
The ink jet recording element of the invention provides a fast ink dry time and good image quality.
The substrate used in the invention may be porous such as paper or non-porous such as resin-coated paper; synthetic paper, such as Teslin(copyright) or Tyvek(copyright); an impregnated paper such as Duraform(copyright); cellulose acetate or polyester films. The surface of the substrate may be treated in order to improve the adhesion of the image-receiving layer to the support. For example, the surface may be corona discharge treated prior to applying the image-receiving layer to the support. Alternatively, an under-coating or subbing layer, such as a layer formed from a halogenated phenol or a partially hydrolyzed vinyl chloride-vinyl acetate copolymer, can be applied to the surface of the support.
Any inorganic particle may be used in the invention, such as metal oxides or hydroxides. In a preferred embodiment of the invention, the metal oxide is silica available commercially as Nalco(copyright) (Nalco Co.), Ludox(copyright) (DuPont Corp), Snowtex(copyright) (Nissan Chemical Co.), alumina, zirconia or titania. In another preferred embodiment of the invention, the particle size of said particles is from about 5 nm to about 1000 nm.
The encapsulated particles used in the invention may be prepared by silane coupling chemistry to modify the surface of inorganic colloids, followed by emulsion polymerization which can be found in xe2x80x9cEmulsion Polymerization and Emulsion Polymersxe2x80x9d, edited by P. A. Lovell and M. S. El-Aassar, John Wiley and Sons, 1997.
Silane coupling agents useful for the modification of inorganic colloids include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyldiethoxymethylsilane, 3-aminopropyldimethoxymethylsilane, 3-aminopropylethoxydimethylsilane, 3-aminopropylmethoxydimethylsilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyl dimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, 4-aminobutyltriethoxysilane, 4-aminobutyltrimethoxysilane, N-(2-aminoethyl)-3-aminoisobutylmethyldimethoxysilane, and other silane coupler agents listed in Gelest catalogue, pp.105-259(1997). Most preferred silane coupling agents for the modification of inorganic colloids used in the invention include 3-aminopropyl-triethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyldiethoxymethylsilane, 3-aminopropyldimethoxymethylsilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysitane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane.
The organic polymer used for encapsulation of the inorganic particles employed in the invention has a Tg of less than about 20xc2x0 C. preferably from about xe2x88x9250xc2x0 C. to about 20xc2x0 C. Examples of these polymers which may be used in the invention include homo- and copolymers derived from the following monomers: n-butyl acrylate, n-ethylacrylate, 2-ethylhexylacrylate, methoxyethylacrylate, methoxyethoxy-ethylacrylate, ethoxyethylacrylate, ethoxyethoxyethylacrylate, 2-ethylhexyl-methacrylate, n-propylacrylate, hydroxyethylacrylate, etc. and cationic monomers such as a salt of trimethylammoniumethyl acrylate and trimethylammoniumethyl methacrylate, a salt of triethylammoniumethyl acrylate and triethylammonium-ethyl methacrylate, a salt of dimethylbenzyl-ammoniumethyl acrylate and dimethylbenzylammoniumethyl methacrylate, a salt of dimethylbutylammoniumethyl acrylate and dimethylbutylammoniumethyl methacrylate, a salt of dimethylhexylammoniumethyl acrylate and dimethylhexylammoniumethyl methacrylate, a salt of dimethyloctyl-ammoniumethyl acrylate and dimethyloctylammoniumethyl methacrylate, a salt of dimethyldodeceylammoniumethyl acrylate and dimethyldocecyl-ammoniumethyl methacrylate, a salt of dimethyloctadecylammoniumethyl acrylate and dimethyloctadecylammoniumethyl methacrylate, etc. Salts of these cationic monomers which can be used include chloride, bromide, methylsulfate, triflate, etc.
Examples of the organic polymers which can be used in the invention include poly(n-butylacrylate-co-vinylbenzyltrimethylammonium chloride), poly(n-butylacrylate-co-vinylbenzyltrimethylammonium bromide),poly(n-butylacrylate-co-vinylbenzyldimethylbenrylammonium chloride) and poly(n-butylacrylate-co-vinylbenzyldimethyloctadecylammonium chloride). In a preferred embodiment of the invention, the polymer can be poly(n-butyl acrylate), poly(2-ethylhexyl acrylate) poly(methoxyethylacrylate), poly(ethoxyethylacrylate), poly(n-butylacrylate-co-trimethylammoniumethyl acrylate), poly(n-butylacrylate-co-trimethylammoniumethyl methacrylate) or poly(n-butylacrylate-co-vinylbenzyltrimethylammonium chloride).